Hydraulically or liquid pressure operated brake



Feb. 18,1936. ou 2,031,360

HYDRAULICALLY 0R LIQUID PRESSURE QPERATED BRAKE Filed May 29, 1933 2 Sheets-Sheet l Feb. 18, 1936.

HYDRAULICALLY on LIQUID PRESSURE OPERATED BRAKE Filed May 29, 1933 2 Sheets-Sheet 2 E. B. BOUGHTON 2,031,360

55 tions.

Patented. Feb. 18,. 1936 v UNITED STATES PATENT OFFICE HYDRAULICALLY a LIQUID rmissuan OPERATED BRAKE EdwardBishop Boughton, London, Eng

signor to Lockheed Hydraulic Brake Co Limited, London, England Application May 29, 1933, Serial No. 673,527 In Great Britain June 4, 1932 4 Claims. (c fill-54.6)

sure to pressure-liquid in a-brake conduit until,

upon the attainmeht in said liquid of a predeter o mined pressure when the brake friction elements have been moved into contact with their drum or drums, or equivalent, pressure is applied to said liquid solely by a comparatively small diameter high pressure piston movable only as one with the low pressurepiston. Various arrangements have been proposed whereby the low pressure piston is rendered inoperative in the application of pressure to the liquid, and the high pressure piston alone remaining operative, substantially as and when the brake elements come into contact with their drum as a result of the action of the' low pressure piston upon the liquid. It has been proposed, for example, in a case where two coaxial pistons of different diameters serve, the one to take up play in a brake, and the other actually to apply the brake, to render the low pressure piston inoperative by means of a spring-controlled pressure release valve, communicating with the low pressure cylinder. In most cases it has been the custom to permit liquid from the low pressure cylinder to passjluring the presentation of the elements to their drum into the high pressure cylinder, and thence to the brake conduit through bores or grooves at the outer periphery of the high pres-- 45 sure to the pressure liquid in the brake conduit.

An apparatus according to one form of the invention is illustrated by the accompanying diagrammatic drawings, in which there is also indicated a modification, and of which:

50 Figurel is a sectional elevation, and

Figure 2 is a detail view drawn to a larger scale.

Figure 3 is a sectional view of a modification.

. Figure 4 is a view in, section, partly in elevation, showing the valve parts inbrake-applying posi- In accordance with this form of the invention, the rear end ll of a low pressure cylinder l2 opens into a reservoir 3 for pressure liquid in the known manner, a high pressure cylinder l4 extending coaxially of the low pressure cylinder l2 from the 5 forward end of the latter, whilst high and low .pressure pistons l5 and I6, respectively, are

formed as one with a bore extending completely therethrough from end to end. Through the whole of the low pressure piston I6 this bore I1 is 10 of comparatively large diameter, but within the high pressure piston IS the bore I1 is of considerably reduced diarneter; this reduced portion |8 of the bore being hereinafter referred to as the restriction'for the sake of brevity. As will be 5 seen, however, this restriction I!) does not extend rearwardly to the forward face of the low pressure piston l6, and is formed at its rear end as a seating, IQ for a valve; the restriction |8 being formed with a further valve seating 20 at its other end 20 which is substantially level with the front face 0 the high pressure piston l5.

In this form a double ended valve is built up I from two main parts, namely, a stem 2| formed integrally with one valve 22 asa head, and an- 5 other valve 23 adapted to be secured in position as shown at the other end of the stem 2| by means of a nut 24 in threaded relationship with the latter. The doublevalve 22, 23 is placed in position by inserting the stem 2| into thehigh 30 pressure piston end of the bore ll until the threaded end of the stem 2| extends beyond the low pressure piston end of ther'estriction it; then the valve 23 directed towards the valve 22 is passed over the threaded end ofthe stem 2| against a 35. shoulder thereon, and is secured in this position by means of a nut 24. The valves 22, 23 of this double valve are thus rigidly connected as one at a distance apart slightly greater than the distance separating the valve seatings l9 and 20 at 40 the ends of the restriction l8 in the bore I l. The usual rubber cupped washer, indicated at 25, of the high pressure piston I5 is formed with a central aperture, the margin, indicated at 25, of

which'bears against the peripheral margin of the outer/face 21 of the valve 22.

An operating spindle 28 extends through the upper part of the liquid reservoir |3in the known manner, and has fast thereon an operating lever 29, which, instead of bearing directly against the ing end of the interconnected valves 22, 23 a coiled compression spring 32. The restriction l8 has a port 33 extending radially therefrom into the low pressure cylinder 12 at the front side of the low pressure piston l6, and through the apertures 3| in the cap the bore l1 communicates with the reservoir l3. Thus, whilst the head valve 22 of the double valve 22, 23 controls liquid flow from one cylinder to the other, so the other valve 23 serves to control liquid flow from the low pressure cylinder l2 to the reservoir Normally, thespring 32 maintains the double valve 22, 23 in a position in which the head valve ,22 is open and permits liquid flow between the cylinders l2 and I4, and in which the other valve 23 is closed preventing liquid flow therethrough from the reservoir l3 to the low pressure cylinder I 2. It will be observed that normally, and also when the head valve 22 is closed, the inner margin 26 of the cupped washer 25 bearing on the outer face 21 of the headvalve 22 prevents liquid flow from thehigh pressure cylinder ll to the low pressure cylinder l2. er 25 constitutes in this way a non-return valve closing the forward end of the restriction l8 against liquid flow from the high pressure cylinder ll.

In operation, the two pistons I5 and "5 ,are moved as one towards the forward ends of their cylinders l4, I2, respectively, and, as a result, liq- 26 of the cupped washer 25 into the high pressure cylinder II and brake conduit (not shown). This continues until the brake shoes or other elements (not shown) coming into contact with their drum (not shown) and all the slack in the system having been taken up, liquid ceases to flow from the restriction 18 into the high pressure cylinder 14. Immediately this liquid flow ceases theiinner margin 25 of the cupped washer 25 seats again upon the outer face 21 of the valve 22, thus preventing from this instant liquid flow from the high pressure cylinder l4 to the restriction 18. Pressure then increases in the high pressure cylinder I4 and when this reaches a predetermined value according to the strength of the spring 32, the latter will yield and the interconnected valves 22, 23 will move to positions in which the valve 22 is seated to act in conjunction with the cupped washer 25 seating in turn upon its outer face to prevent liquid flow fromthe high to the low pressure cylinders the other valve 23 being opened simultaneously to permit liquid flow from the low pressure cylinder l2, through the bore l1 and apertures 3|, to the reservoir l3.

In some cases, as in Figure 3, the double valve 22, 23 together with an apertured elastic washer may be located in a restriction 34 connected intermediately of its length, as indicated at 35,

' with the low pressure cylinder, of a cylinder or other closed chamber 36 separate ffiom the high and low pressure pistons and which is connected at one side of said restriction 34 with the high pressure cylinder, as indicated at ,31, and at the other side with the reservoir, as indicated at 38. The 'three connections 35, 31 and 38 just mentioned may take the form of conduits, and what may be termed the control cylinder or equivalent 36 may be located in any convenient position, which may be at some considerable distance from the actual high and low pressure cylinders. In

The cupped washthe drawings the interconnected valves in the restriction 34 are indicated at 33 and 40, their controlling spring at 4|, and the elastic washer at 42.

It will be observed that whether or not the double valve and associated apertured elastic member be located within the double master piston, a separate liquid reservoir may be employed.

What I claim is:

1. A fluid pressure means for use in a hydraulic brake system of the type having a liquid reservoir, a high pressure cylinder, a low pressure cylinder, a passage therebetween, a communication between said reservoir and one end of said passage, communication between said high pressure cylinder and the other end of said passage, communication between said low pressure cylinder and said passage at a point intermediate said reservoir and high pressure communications with said passage, a' double-valve unit spring-influenced to close normally by one end thereof said reservoir communication and movable in the passage to close by the other end thereof said high pressure cylinder communication and constituting a means closing the high pressure'cylinder communication against liquid flow from the high pressure cylinder, an apertured elastic member normally cooperating at the margin of the aperture together with the other end of the double valve unit for valve closing function.

2. A fluid pressure means for use in a hydraulic brake system of the type having a liquid reservoir,

a high pressure cylinder and piston, a low pressure cylinder and piston, a passage within and opening at the front face of the high pressure piston, communication between said reservoir and said passage, pommunication between the low pressure cylinder and said passage at a point intermediate the opening thereof at the front face of the high pressure piston and said low pressure cylinder communication with said passage, 8. double valve unit spring-influenced to close normallyby one end thereof said reservoir communication and movable in the passage to close by the other end thereof the opening of said passage at the front face of the high pressure piston, and constituting a means closing the opening of the passage at the front of the high pressure piston against liquid flow from the high pressure cylinder, an apertured cupped washer of elastic material which normally cooperates at the margin of the aperture therein with said other end of said double-ended valve for valve closing function, said cupped washer having sealing cooperation with the front face of the high pressure piston and with the walls of the high pressure cylinder.

3. A fluid pressure means for use in a hydraulic brake system of the type having a liquid reservoir, coaxial high and low pressure cylinders, of which the latter opens at its rear end into said reservoir, integral coaxial high and low pressare pistons, a passage extending completely through said integral pistons from the front face of the former to the rear of the latter, a restriction in said passage extending fromthe neighborhood of the front end of the latter toward the rear end thereof, two oppositely directed valve seatings formed at the front and rear'ends respectively of the restriction, one port extending from the restriction to the low pressure cylinder, 2:. double valve unit extending through the restriction from end to end and having two oppositely directed faces corresponding with the seatings at the ends of the restriction, a coiled compression spring located in the passage in rear of the restriction and hearing at one end upon the rear end of the double valve, an apertured cap member at the rear end 01'- the passage and constituting an abut ment for the other end of said spring, and constituting a means closing the front end of the passage against liquid flow from the high pressure cylinder, an apertured. elastic member at 10 the front face of the high pressure piston which normally cooperates at the margin of the aperture therein with the front end of the double valve unit for valve closing function.

4. A fluid pressure means as in claim 1, wherein the double valve unit is operative in a restriction formed intermediate the length of a closed chamber connected at one side of the restriction with the high pressure cylinder and at the other with the reservoir.

EDWARD BISHOP BOUGHTON. 

